A:分子量发生变化
B:基因发生改变
C:氨基酸序列发生改变
D:空间结构发生改变
①因为____,所以英子鼓起勇气微笑着面对生活。
②金吉娅用妈妈给的二十美元____。
③提铅锤的实验成功了,主要是因为____
His failure made his father think him a ___________ boy.